001/*
002 * This library is part of OpenCms -
003 * the Open Source Content Management System
004 *
005 * Copyright (c) Alkacon Software GmbH & Co. KG (https://www.alkacon.com)
006 *
007 * This library is free software; you can redistribute it and/or
008 * modify it under the terms of the GNU Lesser General Public
009 * License as published by the Free Software Foundation; either
010 * version 2.1 of the License, or (at your option) any later version.
011 *
012 * This library is distributed in the hope that it will be useful,
013 * but WITHOUT ANY WARRANTY; without even the implied warranty of
014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015 * Lesser General Public License for more details.
016 *
017 * For further information about Alkacon Software, please see the
018 * company website: https://www.alkacon.com
019 *
020 * For further information about OpenCms, please see the
021 * project website: https://www.opencms.org
022 *
023 * You should have received a copy of the GNU Lesser General Public
024 * License along with this library; if not, write to the Free Software
025 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
026 */
027
028package org.opencms.util;
029
030import org.opencms.jsp.util.CmsJspContentAccessValueWrapper;
031
032import java.util.Collection;
033import java.util.Enumeration;
034import java.util.HashMap;
035import java.util.List;
036import java.util.Map;
037import java.util.Set;
038
039import org.apache.commons.collections.Transformer;
040import org.apache.commons.collections.map.LRUMap;
041import org.apache.commons.collections.map.LazyMap;
042
043/**
044 * Provides Map wrapping utility functions for Java generics.<p>
045 *
046 * @since 8.0.0
047 */
048public final class CmsCollectionsGenericWrapper {
049
050    /**
051     *  Wrapper for lazy maps providing a better containsKey implementation.<p>
052     *
053     * @param <K> the key type
054     * @param <V> the value type
055     */
056    public static class MapWrapper<K, V> implements Map<K, V> {
057
058        /** The wrapped map. */
059        private Map<K, V> m_map;
060
061        /**
062         * Constructor.<p>
063         *
064         * @param map the map to wrap
065         */
066        MapWrapper(Map<K, V> map) {
067
068            m_map = map;
069        }
070
071        /**
072         *
073         * @see java.util.Map#clear()
074         */
075        @Override
076        public void clear() {
077
078            m_map.clear();
079        }
080
081        /**
082         * @see java.util.Map#containsKey(java.lang.Object)
083         */
084        @Override
085        public boolean containsKey(Object key) {
086
087            V value = m_map.get(key);
088            if (value instanceof CmsJspContentAccessValueWrapper) {
089                return ((CmsJspContentAccessValueWrapper)value).getExists();
090            } else {
091                return value != null;
092            }
093        }
094
095        /**
096         * @see java.util.Map#containsValue(java.lang.Object)
097         */
098        @Override
099        public boolean containsValue(Object value) {
100
101            return m_map.containsValue(value);
102        }
103
104        /**
105         * @see java.util.Map#entrySet()
106         */
107        @Override
108        public Set<java.util.Map.Entry<K, V>> entrySet() {
109
110            return m_map.entrySet();
111        }
112
113        /**
114         * @see java.util.Map#equals(java.lang.Object)
115         */
116        @Override
117        public boolean equals(Object o) {
118
119            return m_map.equals(o);
120        }
121
122        /**
123         * @see java.util.Map#get(java.lang.Object)
124         */
125        @Override
126        public V get(Object key) {
127
128            return m_map.get(key);
129        }
130
131        /**
132         * @see java.util.Map#hashCode()
133         */
134        @Override
135        public int hashCode() {
136
137            return m_map.hashCode();
138        }
139
140        /**
141         * @see java.util.Map#isEmpty()
142         */
143        @Override
144        public boolean isEmpty() {
145
146            return m_map.isEmpty();
147        }
148
149        /**
150         * @see java.util.Map#keySet()
151         */
152        @Override
153        public Set<K> keySet() {
154
155            return m_map.keySet();
156        }
157
158        /**
159         * @see java.util.Map#put(java.lang.Object, java.lang.Object)
160         */
161        @Override
162        public V put(K key, V value) {
163
164            return m_map.put(key, value);
165        }
166
167        /**
168         * @see java.util.Map#putAll(java.util.Map)
169         */
170        @Override
171        public void putAll(Map<? extends K, ? extends V> m) {
172
173            m_map.putAll(m);
174        }
175
176        /**
177         * @see java.util.Map#remove(java.lang.Object)
178         */
179        @Override
180        public V remove(Object key) {
181
182            return m_map.remove(key);
183        }
184
185        /**
186         * @see java.util.Map#size()
187         */
188        @Override
189        public int size() {
190
191            return m_map.size();
192        }
193
194        /**
195         * @see java.util.Map#values()
196         */
197        @Override
198        public Collection<V> values() {
199
200            return m_map.values();
201        }
202
203    }
204
205    /**
206     * Hides the public constructor.<p>
207     */
208    private CmsCollectionsGenericWrapper() {
209
210        // empty
211    }
212
213    /**
214     * Provides a wrapper to access the {@link LazyMap} functionality that avoids warnings with Java 1.5 generic code.<p>
215     *
216     * @param <K> the type of keys maintained by the returned map
217     * @param <V> the type of mapped values
218     * @param T the transformer to use for the Lazy Map
219     *
220     * @return a {@link LazyMap} of the required generic type
221     */
222    public static <K, V> Map<K, V> createLazyMap(Transformer T) {
223
224        return new MapWrapper<K, V>(LazyMap.decorate(new HashMap<K, V>(), T));
225    }
226
227    /**
228     * Provides a wrapper to create a {@link LRUMap} that avoids warnings with Java 1.5 generic code.<p>
229     *
230     * @param <K> the type of keys maintained by the returned map
231     * @param <V> the type of mapped values
232     *
233     * @return a {@link LRUMap} of the required generic type
234     */
235    @SuppressWarnings("unchecked")
236    public static <K, V> Map<K, V> createLRUMap() {
237
238        return new LRUMap();
239    }
240
241    /**
242     * Provides a wrapper to create a {@link LRUMap} with the given size that avoids warnings with Java 1.5 generic code.<p>
243     *
244     * @param <K> the type of keys maintained by the returned map
245     * @param <V> the type of mapped values
246     * @param size the initial size of the created Map
247     *
248     * @return a {@link LRUMap} with the given size of the required generic type
249     */
250    @SuppressWarnings("unchecked")
251    public static <K, V> Map<K, V> createLRUMap(int size) {
252
253        return new LRUMap(size);
254    }
255
256    /**
257     * Provides a wrapper to convert an enumeration that avoids warnings with Java 1.5 generic code.<p>
258     *
259     * @param <K> the type of the returned enumeration elements
260     * @param enumeration the enumeration to be converted
261     *
262     * @return a {@link Enumeration} with the required generic type
263     */
264    @SuppressWarnings("unchecked")
265    public static <K> Enumeration<K> enumeration(Enumeration<?> enumeration) {
266
267        return (Enumeration<K>)enumeration;
268    }
269
270    /**
271     * Provides a wrapper to convert an object into a list that avoids warnings with Java 1.5 generic code.<p>
272     *
273     * @param <K> the type of the returned list elements
274     * @param o the object to be converted
275     *
276     * @return a {@link List} with the required generic type
277     */
278    @SuppressWarnings("unchecked")
279    public static <K> List<K> list(Object o) {
280
281        return (List<K>)o;
282    }
283
284    /**
285     * Provides a wrapper to convert an object into a map that avoids warnings with Java 1.5 generic code.<p>
286     *
287     * @param <K> the type of keys maintained by the returned map
288     * @param <V> the type of mapped values
289     * @param o the object to be converted
290     *
291     * @return a {@link Map} of the required generic type
292     */
293    @SuppressWarnings("unchecked")
294    public static <K, V> Map<K, V> map(Object o) {
295
296        return (Map<K, V>)o;
297    }
298}